Effects of the positioning of the child in the family and community were studied for 80 Portuguese students, ages 10 to 12 years, of differing race, social class, and gender. Positioning is considered to be a factor that reflects power and control relations in family hierarchical structures, and one that is particularly influenced by family communication. It was hypothesized that children with a high position in the family would have better academic achievement as well. Positioning in family and community was determined through student questionnaires. Children from advantaged social classes tend to have a more positive perception of their parents' status, and they tend to communicate with parents so that their personal attributes are more valued. Children with high positioning in the family have higher initial achievement in sciences than children with low positioning, but this difference loses significance after 2 years. Low positioning seems to have a more depressing effect on the initial achievement of girls than of boys, but effects of race were not separable from those of social class in this sample. Results suggest that school pedagogic practice may blur the effect of positioning on academic achievement. Five figures illustrate the discussion. (Contains 13 references.) (SLD)